▎ 摘　　要

Pd-graphene nanosheets are synthesized by a mild condition. Structures and morphologies of samples are characterized by transmission electron microscopy (TEM) images, and field-emission scanning electron microscope (FE-SEM). The concentration of N2H4 affects the size of Pd nanocrystals. More importantly, the size of nanocatalyst greatly affects its electrochemical activity towards electrocatalytic oxidation of formic acid. We find that the sub-3 nm Pd-graphene nanosheets exhibit much higher formic acid oxidation activity.